Ventriculoarterial coupling in valvular heart disease

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Ventriculo-arterial coupling in valvular heart
disease

• Renato Razzolini

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PRESSURE-VOLUME LOOP
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PERIPHERAL (ARTERIOLAR) RESISTANCE (R)

• Peripheral (arteriolar) Resistance is the ratio
  between mean aortic pressure (Pao) and mean left
  ventricular antegrade output (Qa).

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EFFECTIVE AFTERLOAD (Ea)

• Effective afterload is the ratio between left
  ventricular end systolic pressure (Pes) and left
  ventricular stroke volume (SV).

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CONTRACTILITY (Es)
Contractility is the ratio between left
ventricular end systolic pressure (Pes) and left
ventricular end systolic volume (ESV).
Pes
Ea
ESV
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Pao Mean aortic pressure Plv Mean left
ventricular pressure Pes Left ventricular end
systolic pressure Plvs Mean left ventricular
systolic pressure
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QUESTION 1

• Is there any relationship between Resistance (R),
  and Effective Afterload (Ea)?
• Q SV HR
• Pes/R SV HR
• Pes/SV R HR Ea R HR
• HR Heart Rate Q Cardiac output SV Stroke
  volume

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Ea induced modifications on pressure-volume loop
Ees Pressione sistolica / volume
telesistolico Ea Pressione sistolica / gettata
sistolica
Normalmente Ea/Ees lt1 Nello scompenso Ea/Ees
gt 1
PRESSURE
Ees
Ea
VOLUME
LVEDV
Ea R HR
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ANSWER 1

• The relation between Peripheral Resistance (R)
  and Ea is linear only in normal subjects, not in
  patients with diastolic overload.

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EFFECTIVE AFTERLOAD/RESISTANCE
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QUESTION 2

• What is the nature of the relation between
  Resistance (R) and Effective Afterload (Ea), both
  in normal and in diastolic overloaded hearts?

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• We can answer this question by having recourse to
  the Windkessel model, which relates left
  ventricular end systolic pressure (Pes, Plvs,
  dicrotic notch) to the arterial Resistance (R)
  and Compliance (C), and to the duration of
  systole and diastole.

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QUESTION 3

• What can be a practical application of these
  concepts?

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EXAMPLES OF CLINICAL APPLICATIONS

• 1. Measurement of the left ventricular end
  systolic pressure
• 2. Measurement of peripheral Resistance in
  aortic insufficiency
• 3. Estimation of regurgitating volumes in mitral
  and aortic insufficiency
• 4. Prediction of the effects of interventions on
  left ventricular function

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• In acute setting, a decrease in Ea results in an
  increase in left ventricular end diastolic
  volume, unless either left ventricular end
  systolic pressure decreases, or the heart rate
  increases (the increase in heart rate makes Ea to
  increase)
• LVEDV Pes (1/Ea 1/Es)

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Ea induced modifications on pressure-volume loop
Ees Pressione sistolica / volume
telesistolico Ea Pressione sistolica / gettata
sistolica
Normalmente Ea/Ees lt1 Nello scompenso Ea/Ees
gt 1
PRESSURE
Ees
Ea
VOLUME
LVEDV
Ea R HR
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Modifications of Ea on pressure-volume loop
Ea RHR
Ea
Ea'
Es
Control
Ea"
Vasodilation
... decreased Pes
PRESSURE
... increased HR
LVEDV
'
VOLUME
LVEDV
LVEDV"
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HYDRALAZINE IN MITRAL INSUFFICIENCY
Greenberg BH et al Beneficial effects of
Hydralazine in severe mitral regurgitation.
Circulation 1978 58273-279.
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HYDRALAZINE IN AORTIC INSUFFICIENCY
Greenberg BH et al Mechanisms for improved
cardiac performance with arteriolar dilators in
aortic insufficiency. Circulation 1981
63263-268.
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NIFEDIPINE IN AORTIC INSUFFICIENCY
Scognamiglio R et al Long-term nifedipine
unloading therapy in asymptomatic patients with
chronic severe aortic regurgitation. J Am Coll
Cardiol 1990 16430-432.
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conclusions Long-term vasodilator therapy with
nifedipine or enalapril did not reduce or delay
the need for aortic-valve replacement in patients
with asymptomatic severe aortic regurgitation and
normal left ventricular systolic function.
Furthermore, such therapy did not reduce the
aortic regurgitant volume, decrease the size of
the left ventricle, or improve left ventricular
function.
n engl j med 35313-29, 2005
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MITRAL INSUFFICIENCY
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MITRAL INSUFFICIENCY
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AORTIC INSUFFICIENCY
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AORTIC INSUFFICIENCY
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SOURCE RESISTANCE/EFFECTIVE AFTERLOAD
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CONCLUSIONS

• Effective Afterload - Contractility paradigm
  describes ventriculo-arterial coupling in
  valvular heart diseases.
• It can predict cardiovascular behavior after
  interventions that alter contractility,
  peripheral resistances or heart rate.

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SOURCE RESISTANCE

• NORMAL SUBJECTS (N) 0.765
• MITRAL INSUFFICIENCY (M) 0.453
• AORTIC INSUFFICIENCY (A) 0.612

Test ANOVA N ltgt M A p 0.025
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CONCLUSIONS

• It demonstrates that mean left ventricular
  systolic pressure equals left ventricular end
  systolic pressure in normal and diseased
  patients.
• It allows a correct determination of peripheral
  resistance in aortic insufficiency.